This invention relates generally to object identification systems, and more particularly to portable object identification systems and methods for communicating with a remote host system.
Shipping containers, pallets, railroad cars, automobiles and the like need to be identified while they are in use. Systems for remote identification using active or passive "tags" which back scatter modulate a continuous wave reflecting a modulated signal with a digital identification code have been described in U.S. Pat. Nos. 4,739,328, and 4,888,591, assigned to the same assignee as this invention. The back scatter modulated signal is received, usually by the same system which transmitted the original signal (source), and the digital code is demodulated and decoded, providing identity information which may be processed as desired.
In many applications of these systems, the objects seeking to be identified are located in an environment which does not facilitate the use of a fixed reader system. In these kinds of systems, a portable reader may be employed to recover object data, and thereafter communicate that data with a base unit located remotely. Accordingly, the portable reader must be able to store the information recovered (for uploading at a future time) or alternatively be fitted with a transmission source for real time transmission of the information back to a base unit.
One good example is in a cargo ship environment. Typically, cargo ships transport containers which may be destined for off loading at various ports along the cargo ship's route. It would be desirable to be able to attach to each shipping container an electronic tag which identified the destination port for each container, to assist loading the cargo ship and to assure the proper off loading of each container. A portable unit capable of reading the electronic tag information would be desirable in such an environment. Ideally, such a portable reader would be capable of (1) reading the identification information stored in the tag associated with a given container and (2) displaying the relevant information upon a successful read. In addition, the portable unit should be small (hand held), operate on minimum power and be capable of transmitting the information to a base unit for processing in real time.
In some environments the attachment of an electronic tag to a package or container may not be feasible or cost effective. Other means of identifying a particular object may be required. For example, objects may be identified by the use of a bar code. Alternatively, a textual code (serial number or the like) may be employed. Accordingly, the identification of an object may require multiple readers depending on the format of the object identifiers employed.